5:15 PM - 7:15 PM
[AAS11-P26] Assessing the impact of CO2 emissions from China on Japan’s coastal regions by using excess concentration ratios from GOSAT and GOSAT-2
Keywords:GOSAT, GOSAT-2, fossil fuel CO2, ER
China is one of the largest carbon dioxide (CO2) emission regions and Japan’s coastal regions are affected by these emissions [Tohjima et al., 2014]. We have analyzed XCO2 and XCH4 data obtained from GOSAT and GOSAT-2 satellite observations in the three land regions in China (East China, North China, and South China) and East China Sea and Japan Sea. In order to evaluate the impact of fossil fuel CO2 emissions from Mainland China on Japanese ocean regions, we calculated excess concentrations of XCO2 and XCH4 relative to their background concentrations (ΔXCO2 and ΔXCH4) using the satellite data, and then calculated Enhancement Ratio (ER) by taking the ratios of ΔXCO2 and ΔXCH4 for the three land regions in China and the two ocean regions. We also compared the calculated ER values with the EDGAR CO2 and CH4 inventory database to investigate the emission source of CO2 in each of the three land regions in China.
In North and East China, the calculated ER values (ΔXCO2/ΔXCH4) and correlation coefficients were higher especially in winter and summer. These seasonal variations were consistent with the seasonal variations of CO2 emissions from the power industry there, which suggests that the higher ER values were caused by CO2 emissions from the power industry. In South China, the ER values were also higher in winter, which suggests the influence of CO2 emissions from the power industry; in contrast, they were lower in summer, which is caused by high CH4 emissions from agriculture there. Over the ocean regions where there are no major CO2 and CH4 emission sources, the monthly ER values were the highest in February and March. Our backward trajectory analysis showed that airmasses were transported from North and East China to East China Sea and from North China to Japan Sea in February, which suggests that airmass with high CO2 concentrations emitted by fossil fuel combustion on Mainland China were transported by the East Asian winter monsoon and is consistent with the conclusions of the previous studies based on surface observations over Hateruma Island [Tohjima et al., 2014; 2020]. Seasonal variations of ΔXCH4/ΔXCO2 based on GOSAT and GOSAT-2 observations also showed a good agreement to those based on the surface observations over Hateruma Island [Tohjima et al., 2014], which demonstrates the validity of our satellite-based ER analysis.
In North and East China, the calculated ER values (ΔXCO2/ΔXCH4) and correlation coefficients were higher especially in winter and summer. These seasonal variations were consistent with the seasonal variations of CO2 emissions from the power industry there, which suggests that the higher ER values were caused by CO2 emissions from the power industry. In South China, the ER values were also higher in winter, which suggests the influence of CO2 emissions from the power industry; in contrast, they were lower in summer, which is caused by high CH4 emissions from agriculture there. Over the ocean regions where there are no major CO2 and CH4 emission sources, the monthly ER values were the highest in February and March. Our backward trajectory analysis showed that airmasses were transported from North and East China to East China Sea and from North China to Japan Sea in February, which suggests that airmass with high CO2 concentrations emitted by fossil fuel combustion on Mainland China were transported by the East Asian winter monsoon and is consistent with the conclusions of the previous studies based on surface observations over Hateruma Island [Tohjima et al., 2014; 2020]. Seasonal variations of ΔXCH4/ΔXCO2 based on GOSAT and GOSAT-2 observations also showed a good agreement to those based on the surface observations over Hateruma Island [Tohjima et al., 2014], which demonstrates the validity of our satellite-based ER analysis.